Dielectric loss of niobium-doped and undoped polycrystalline Sr2Bi4Ti5O18

2005 ◽  
Vol 20 (4) ◽  
pp. 971-974 ◽  
Author(s):  
Wang-ping Lu ◽  
Jun Zhu ◽  
Hui Sun ◽  
Xiao-bing Chen
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Remnant Polarization ◽  
Oxygen Vacancies ◽  
Relaxation Mechanism ◽  
Annealing Atmosphere ◽  
Niobium Doping ◽  
Vanadium Doping ◽  
Niobium Doped ◽  
Nb Doping

Ferroelectric and dielectric properties of niobium-doped Sr2Bi4Ti5O18 ceramics were investigated. Compared with the undoped ceramics, the niobium-doped ceramics exhibited obviously increased remnant polarization 2Pr, which is similar to the case of vanadium doping. However, the mechanisms of increasing of 2Pr by vanadium and niobium doping are quite different. In the case of Nb-doping, one relaxation peak P1 is found on the dielectric loss curves D(T) at 70 °C. The dependence of the peak on various annealing atmosphere indicates that the relaxation mechanism of the peak is related to oxygen vacancies. With niobium doping, the P1 peak declines gradually. These results suggest that the substitution of Ti4+ by a small amount of Nb5+ can result in the decreasing of the concentration of oxygen vacancies. Thus, the increase in 2Pr of Nb-doped Sr2Bi4Ti5O18 could be attributed to the significant weakening of defect pinning.

Dielectric Properties of BiFeO3 Ceramics with Equal and Unequal Substitutions of Ti for Fe

2010 ◽  
Vol 434-435 ◽  
pp. 278-280
Author(s):  
Yan Hong Gu ◽  
Wan Ping Chen ◽  
Ming Jian Ding ◽  
Jian Quan Qi
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Dielectric Loss ◽  
Oxygen Vacancies ◽  
Solid State Reactions ◽  
Defect Complexes ◽  
Electrical And Dielectric Properties

BiFeO3, BiFe0.9Ti0.1O3 and BiFe0.9Ti0.05O3 ceramics were prepared by solid state reactions and were compared in electrical and dielectric properties. The resistivity of BiFe0.9Ti0.05O3 was 1.3×1012 Ω cm, which was about two and a half orders of magnitude higher than that of BiFeO3. and three times higher than that of BiFe0.9Ti0.1O3. The dielectric loss of BiFe0.9Ti0.05O3 was 0.1 and 0.02 at 100Hz and 1MHz, respectively. These phenomena can be explained base on the decrease of oxygen vacancies VO•• and defect complexes between the ferrum vacancies VFe and oxygen vacancies VO•• in the ceramics.

Electrical Properties of Bismuth-Layered Structural CaxSr2-xBi4Ti5O18 Ceramics

2010 ◽  
Vol 105-106 ◽  
pp. 282-285 ◽  
Author(s):  
Su Hua Fan ◽  
Feng Qing Zhang ◽  
Q.D. Che ◽  
R. Yu ◽  
W. Hu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Remnant Polarization ◽  
Single Phase ◽  
Ferroelectric Properties ◽  
Secondary Phase ◽  
Ferroelectric Ceramics ◽  
Layered Perovskite

Effects of amount of Ca on crystal structure, microstructure, ferroelectric properties, and dielectric properties of the CaxSr2-xBi4Ti5O18 (CSBTi-x) ferroelectric ceramics were investigated. The results show that single-phase layered perovskite ferroelectrics were obtained and no appreciable secondary phase was found.Ca-doping results in a notable enlargement of remnant polarization 2Pr. The 2Pr of CSBT-0.15 reaches a large value, the remnant polarization 2Pr and coercive field 2Ec were 18.1µC/cm2 and 120.2kV/cm, respectively. Dielectric constant and dielectric loss of CSBT-0.15 was also measured, showing dielectric constant εr=199~194 and dielectric loss tanδ=0.02~0.014 over the range of 100 kHz~1MHz, respectively.

Microstructure and Microwave Dielectric Properties of BaTi4O9 Ceramics Derived from a Sol-Gel Precursor

2011 ◽  
Vol 326 ◽  
pp. 127-130
Author(s):  
Xian Li Huang ◽  
Fu Ping Wang ◽  
Ying Song
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Sol Gel ◽  
Microwave Dielectric Properties ◽  
Sintering Process ◽  
Temperature Coefficients ◽  
Microwave Dielectric ◽  
Ceramic Samples ◽  
Quality Factor Q

In the present work, the microstructure and microwave dielectric properties of BaTi4O9 ceramics derived from a sol-gel precursor were presented. Density measuring results demonstrated that the largest densities of ceramic sample about 96.7% could be reached by virtue of a cool iso-static press and a sintering process at at 1300 °C for 6 hours. The dielectric constant (εr), quality factor (Q×f) and the temperature coefficients (τf) of the BaTi4O9 ceramic samples were 36.65, 28000 GHz, +20.2 ppm/°C, respectively. XRD, SEM and XPS were used to characterize the microstructure of the ceramics samples. Substantial Ti3+ was proposed to be the cause of dielectric loss.

Preparation and Dielectric Properties of 1-3 La Modified PZT/IPN Piezoelectric Composites

2010 ◽  
Vol 105-106 ◽  
pp. 355-358 ◽  
Author(s):  
Z.L. Zhu ◽  
Dong Yan Tang ◽  
X.H. Zhang ◽  
Y.J. Qiao
Keyword(s):  
Heat Treatment ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Lead Zirconate Titanate ◽  
Polymer Network ◽  
Lead Zirconate ◽  
Interpenetrating Polymer Network ◽  
Ceramic Fibers ◽  
Piezoelectric Composites

To prevent the potential cracking of gel fibers, La modified lead zirconate titanate (PLZT) ceramic fibers with diameter within 50µm were achieved by embedding into PLZT powders during the heat treatment. Then the 1-3 PLZT fiber/interpenetrating polymer network (IPN) piezoelectric composites were prepared by casting the IPN precursors onto the well aligned ceramic fibers. The influences of the heating temperatures and La amounts on the dielectric constant, dielectric loss with frequencies and piezoelectric constant of PLZT were investigated in detail. The morphologies of fibers and composites were observed by biological microscope. And also, the dielectric constant of PLZT fibers and PLZT fiber/IPN piezoelectric composites were detected.

Microstructures and microwave dielectric properties of Mg+1Ti O3+1 ceramics with ultralow dielectric loss

2016 ◽  
Vol 185 ◽  
pp. 432-435 ◽  
Author(s):  
Xianpei Huang ◽  
Fei Liu ◽  
Changlai Yuan ◽  
Xinyu Liu ◽  
Jingjing Qu ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Loss ◽  
Microwave Dielectric Properties ◽  
Microwave Dielectric

Microwave Nondestructive Sensing of Moisture Content and Water Activity of Almonds

2021 ◽  
Vol 64 (4) ◽  
pp. 1373-1379
Author(s):  
Samir Trabelsi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Bulk Density ◽  
Water Activity ◽  
Free Space ◽  
Loss Factor ◽  
Dielectric Loss Factor ◽  
List Type

HighlightsMoisture and water activity were determined nondestructively and in real time from measurement of dielectric properties.Moisture and water activity calibration equations were established in terms of the dielectric properties.Situations in which bulk density was known or unknown were considered.SEC ranged from 0.41% to 0.68% for moisture and from 0.02 to 0.04 for water activity.Abstract. A method for rapid and nondestructive determination of moisture content and water activity of granular and particulate materials was developed. The method relies on measurement of the dielectric constant and dielectric loss factor at a single microwave frequency. For the purpose of illustration, the method was applied to predicting the moisture content and water activity of almond kernels. A free-space transmission technique was used for accurate measurement of the dielectric properties. Samples of Bute Padre almond kernels with moisture content ranging from 4.8% to 16.5%, wet basis (w.b.), and water activity ranging from 0.50 to 0.93 were loaded into a Styrofoam sample holder and placed between two horn-lens antennas connected to a vector network analyzer. The dielectric properties were calculated from measurement of the attenuation and phase shift at 8 GHz and 25°C. The dielectric properties increased linearly with moisture content, while they showed an exponential increase with water activity. Situations in which the bulk density was known and unknown were considered. Linear and exponential growth regressions provided equations correlating the dielectric properties with moisture content and water activity with coefficients of determination (r2) higher than 0.96. Analytical expressions of moisture content and water activity in terms of the dielectric properties measured at 8 GHz and 25°C are provided. The standard error of calibration (SEC) was calculated for each calibration equation. Results show that moisture content can be predicted with SECs ranging from 0.41% to 0.68% (w.b.) and water activity with SECs ranging from 0.02 to 0.04 for almond kernel samples with water activity ranging from 0.5 to 0.9 and moisture contents ranging from 4.8% to 16.5% (w.b.). Keywords: Bulk density, Dielectric constant, Dielectric loss factor, Free-space measurements, Loss tangent, Microwave frequencies, Moisture content, Water activity.

The Dielectric Properties of Pb0.65Ba0.35ZrO3 Thin Films

2006 ◽  
Vol 306-308 ◽  
pp. 1313-1318
Author(s):  
J.S. Kim ◽  
B.H. Park ◽  
T.J. Choi ◽  
Se Hyun Shin ◽  
Jae Chul Lee ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Deposition Temperature ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Axis Orientation ◽  
Capacitance Voltage ◽  
Bst Thin Film

Pb0.65Ba0.35ZrO3 (PBZ) thin films have been grown on MgO (001) substrates by pulsed-laser deposition (PLD). We have compared the structural and dielectric properties of PBZ films grown at various temperatures. A highly c-axis orientation has appeared at PBZ film grown at the deposition temperature of 550oC. The c-axis oriented PBZ film has also shown the largest tunability among all the PBZ films in capacitance-voltage measurements. The tunability and dielectric loss of the PBZ film was 20% and 0.00959, respectively. In addition, we have compared the temperature coefficient of capacitance (TCC) of a PBZ film with that of a Ba0.5Sr0.5TiO3 (BST) film which is a well-known material applicable to tunable microwave devices. We have confirmed that TCC value of a PBZ thin film was three-times smaller than that of a BST thin film.

Synthesis and Dielectric Properties of [(K0.5Na0.5)0.935Li0.065]NbO3 Added with Mn for Piezoelectric Ceramic

2016 ◽  
Vol 675-676 ◽  
pp. 635-638
Author(s):  
Jukkrit Kongphimai ◽  
Hassakorn Wattanasarn ◽  
Tosawat Seetawan
Keyword(s):  
Crystal Structure ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Physical Properties ◽  
Crystallite Size ◽  
Piezoelectric Ceramic ◽  
Theoretical Density ◽  
Milling Method ◽  
Xrd Patterns

[(K0.5Na0.5 )0.935Li0.065]NbO3–Mn ceramics (Mn = 0, 1.50 and 3 mol %) (KNNL–Mn) were synthesized and measured dielectric properties. Which the K2CO3, Na2CO3, Li2CO3, Nb2O5 and MnO2 (0, 1.5, 3 mol%) were mixed by ball milling method and calcined powders at 1,073 K for 4 h and the sintered at 1,343 K for 2 h in air. The crystal structure was analyzed by XRD technique, the crystallite size was identified by Scherrer’s equation and calculated the theoretical density. It was found that, the XRD patterns of the KNNL–Mn ceramics added with Mn contents was indicated the tetragonal structure and. the crystallite size of Mn = 0, 1.50 and 3 mol% about 32 nm, 34 nm and 57 nm, respectively. The physical properties of the KNNL–Mn ceramics was found that the maximum theoretical density of 90.79 % for Mn = 1.50 mol%. The dielectric constant was found to be maximum of 909.77 and dielectric loss of 0.48 for Mn = 3 mol%.

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